This invention generally relates to prostheses for the spine and more specifically to an implant to separate adjacent cervical vertebrae.
The spine is the central support column for the human body. The cervical region of the spine is located in the area of the neck and is comprised of cervical vertebrae separated by disks. A diseased spine suffers from deterioration of a vertebra, disk or both. Disks and vertebrae may also be damaged by physical causes as well. Surgical repair consists of fusing adjacent vertebrae together by means of a bone graft. It is necessary to keep the adjacent vertebrae spaced at a certain distance at the time the bone graft is growing and fusing the adjacent vertebrae together. Traditionally, this has been done mechanically. Typically, the systems are comprised of plates and screws or rods and screws.
Intervertebral implants may be used to replace or augment the method of grafting. A problem with grafting is that grafts are not always successful. Resorption of the graft results in a collapse of the area between the vertebrae. A permanent support structure such as an implant will not allow collapse. A problem with prior art intervertebral implants is that most are designed for use in the lumber section of the spine and thus have contoured surfaces which match the contour of the lumbar vertebrae. The cervical vertebrae have contours different from those of the lumbar vertebrae.
Another problem with prior art implants currently being used in the cervical section of the spine is that some implants which are formed as cages do not have superior strength characteristics. An implant which is simple to manufacture and has superior strength is desired.
The present invention overcomes disadvantages in the prior art by providing an improved cervical implant for holding spinal vertebrae apart. The implant is stirrup shaped and includes a ring portion having two legs and an interconnecting section. The legs of the ring portion are connected to a truncation which has a thickness which exceeds the thickness of the ring portion. The legs of the ring portion also includes upper and lower surfaces provided with barbed saw teeth, each tooth defined by a proximal face having a rearward tapered angle and a substantially vertical distal face and a rounded valley between each pair of adjacent teeth.
The invention, in the aspects described above, provides the advantage of a physical support device which prevents the collapse of adjacent vertebrae in the event a bone graft is unsuccessful. This device is easy to insert and has superior strength. These and other features, aspects and advantages of the present invention will be fully described by the following description, appended claims, and accompanying drawings.